Since heat-sensitive recording materials are highly reliable and free of maintenance in spite of their low cost and the simpleness of the recording device using them, they have recently been utilized in various fields such as facsimiles and printers. However, the heat-sensitive recording materials undergo variations in physical properties or recording characteristics with a change of their water content. That is, heat sensitivity on recording and the image density vary depending on the extent of exposure to the outer environment, especially high or low humidity, before recording. Further, the environmental change tends to make the recording material fail to be fed smoothly by means of a paper feed system.
It has been proposed to use a light-screening and/or moistureproof packaging material for packing recording materials susceptible to the influences of the outer environment so as to exclude the outer influences as disclosed, e.g., in JP-B-57-39411 (the term "JP-B" as used herein means an "examined published Japanese patent application") and JP-A-3-134658 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, the recording materials are unavoidably exposed to the outer temperature and humidity after being taken out of the package and loaded on a recording device until recording.
The adverse influence of the outer environment is the problem not only for heat-sensitive recording materials per se but for light-sensitive materials and for paper feed systems in printers.
In order to solve the problem, JP-A-6-92498 proposes a paper feeder for a printer which eliminates paper feed troubles due to changes in temperature and humidity and a paper container to be used therein, in which a desiccator is used to keep the inside of a tray dry. However, the method is disadvantageous in that troubles caused by static electricity or dust tend to occur due to the low humidity and that the moistureproof mechanism is bulky, making it difficult to reduce the device in size.
Thus, none of the conventional techniques has brought about sufficiently satisfactory results.
The inventors of the present invention have conducted extensive studies in pursuit of further improved paper feed performance. As a result they have found that very satisfactory results can be reached by using a tray fitted with an opening-and-closing mechanism or by putting a roll of a heat-sensitive recording material into a magazine and conditioning the inside of the tray or the magazine at a relative humidity (RH) of 35 to 85%. The present invention has been completed based on this finding.